def number_of_videos(video_size, video_unit, drive_size, drive_unit):
    video_units = ['KB', 'MB', 'GB']
    drive_units = ['TB', 'GB']
    if video_unit not in video_units:
        return "Invalid video unit"
    if drive_unit not in drive_units:
        return "Invalid drive unit"
    match video_unit:
        case "KB": video_size *= 1000
        case "MB": video_size *= 1000_000
        case "GB": video_size *= 1000_000_000
    match drive_unit:
        case "GB": drive_size *= 1000_000_000
        case "TB": drive_size *= 1000_000_000_000
    return drive_size // video_size

if __name__ == '__main__':
    print(number_of_videos(500, "MB", 100, "GB"))